I will also talk about the van der Waals material based ultrafast optical optoelectronics. Especially, ultrafast light emitter in nanoscale is a critical component in the development of the high bandwidth on-chip optical interconnects for ubiquitous computing and Big data applications. However, previous technology faces the major challenges such as big footprint, high cost integration and difficulties of direct high speed electrical pumping. Here, I will talk the first electrically driven ultrafast graphene light emitter that exhibits the ultrafast light modulation up to ~ 4 GHz with broad optical bandwidth (400 ~ 1600 nm). Furthermore, atomically thin hexagonal boron nitride (hBN) encapsulation layers to graphene allow the stable and practical high performance even under the ambient condition as well as efficient direct electronic cooling via near-field coupling of hybrid plasmon-phonon polaritonic modes. Ultrafast and broadband graphene light emitter paves the way towards the realization of complete graphene-based ultrafast optical communications.